Common Lisp

Extensible from the Inside-Out

Part of what makes Lisp distinctive is that it is designed to
evolve. As new abstractions become popular (object-oriented
programming, for example), it always turns out to be easy to
implement them in Lisp. Like DNA, such a language does not go out
of style.

Fast

Requests per second using Woo, an HTTP server written in pure Common Lisp.

Great Tools

SLIME, an IDE that leverages the power of Common
Lisp and the extensibility of Emacs, provides a development
environment ahead of anything else.

You can leave the write-compile-debug cycle behind. Everything is
interactive: try your code on the REPL as you write it, and a
powerful debugger lets you inspect trees of live values, or rewind
the stack to undo an exception.

Grammarly is a grammar checking startup, but it’s far more than a
simple spell checker. Its grammar engine, written in Common Lisp, finds
instances of incorrect tenses and suggests more precise synonyms for common
words.

At Grammarly, the foundation of our business, our core grammar engine, is written in Common Lisp. It currently processes more than a thousand sentences per second, is horizontally scalable, and has reliably served in production for almost 3 years.

Lisp was the natural language to start with. We needed to write lots of
code very quickly; and we needed the higher-level power that only Lisp and
Allegro CL provides. Lisp provided us with the ability to write the
algorithms that we needed.

We can search thousands of pricing and scheduling options in the time it
takes the other airline engines to search several hundred. And, thanks to
our lisp-based algorithms, we can adapt our questions to become more
narrow or broad depending on the situation.